Breakthroughs in the United States and Japan allow for stretchable circuits, curved camera chips, and more

ALL-SEEING EYE

Last week, researchers at the University of Illinois, led by materials science professor John A. Rogers, reported in Nature the creation of an electronic eye using an array of photodetectors that can be stretched across the back of an artificial eyeball. This photo shows a completed electronic-eye camera mounted on a printed circuit board. A curved photodetector array, like the human eye’s retina, lets a camera produce sharp images with optics that are less complicated than those required for a planar array, such as the one in a digital camera.

Photo: John A. Rogers/University of Illinois at Urbana-Champaign

STRESS RELIEF

The artificial eye was made possible by breakthroughs in the production of electronics that bend, stretch, and twist. Pictured is a cluster of silicon photodetectors (squares) interconnected by thin, arcing metal ribbons. These arches allow the electronic circuits to be stretched over a round surface like an eyeball or over the corners of a cube.

Photo: John A. Rogers/University of Illinois at Urbana-Champaign

THE CMOS SCRUNCH

Earlier this year, the Illinois team reported that it had produced stretchable circuits, silicon ribbons onto an expanded plastic substrate. When the plastic is allowed to contract, it causes the circuit layer to form folds and wrinkles. These wrinkles are what make it possible to subsequently stretch or fold the circuit without breaking it.

Photo: John A. Rogers/University of Illinois at Urbana-Champaign

POWERFUL PLASTIC

A milestone in bendable circuits came in January when Rogers’s group reported having created CMOS circuits —the digital logic that dominates chips today—on plastic. For the most part, CMOS circuits draw power only when they are switching from one state to another. Low power operation in bendable and stretchable circuits is needed to keep them from melting the plastic substrate. This photo shows a CMOS test circuit called a ring oscillator.

Photo: Science/AAAS

RUBBERY WIRES

Researchers in Japan reported last week in Science that they had produced a stretchable, rubberized electronic circuit sheet. In it, printed organic transistors are connected by newly developed carbon-nanotube-laced polymer interconnects.

Photo: Science/AAAS

BALL GRID ARRAY

The rubberized active matrix—shown here pulled over a spherical object—can be stretched and twisted up to 70 percent beyond its static dimensions without suffering electrical or mechanical damage.